Make Like a Leaf: Next-Gen Paint Could Strike Lotus Pose

Posted: 23 Oct 2009 11:50 AM PDT

Lotus leaves stay dry by using the natural vibrations of their environments to shake off water, and manmade materials should be able to mimic the water-repelling technique.

The new research published today in Physics Review Letters by Duke materials scientist Chuan-Hua Chen has solved a long-standing puzzle: how lotus leaves stay dry in the wild, but not in the lab.

Chen, who grew up surrounded by lotus plants in his hometown of Honghu in central China, had an intuition that perhaps the leaves used the vibrations induced by the wind to stay dry, but that had never been shown in the lab.

So, Chen and his graduate student, Jonathan Boreyko, stuck lotus leaves, on which they'd condensed water, atop the woofer of a $20 Radio Shack speaker to vibrate the leaf at about 100 hertz — and recorded what happened with a very high-speed camera. Just as in their natural state, the leaves stayed dry.

"People have observed that condensation forms every night on the lotus leaf. When they come back in the morning the water is gone and the leaf is dry," Chen said in a press release. "The speaker reproduced in the lab what happens every day in nature, which is full of subtle vibrations, especially for the lotus, which has large leaves atop long and slender stems."

Lotus leaves are the canonical example of a hydrophobic, or water-hating, material. When drops of water fall on the plants, they roll off. They cannot be wet. At the microscopic level, the surfaces are actually quite rough: Tiny fiber-covered pillars hold up the water droplets, creating a cushion of air that prevents them from sticking to the leaves. If water gets into that air cavity though, the property of the material reverses and starts to love water.

Dew, which forms inside the air cavities presented a major problem for researchers looking for hydrophobic coatings for vehicles, say. They worried their materials would be ruined by actual field usage.

"Much remains to be done to achieve genuine antidew materials," summarized French materials scientist David Quere, in a 2008 article in the Annual Review of Materials Research [pdf].

The real problem, though, was that the leaves had not been allowed to move as they would in natural conditions. Now, with the discovery that simple vibration can force every drop of water off the leaf, a roadblock has been cleared for hydrophobic materials.

"This finding has direct applications because vibration is everywhere," Chen told Wired.com. "Your computer has fans, it keeps vibrating. Your power plants, your automobile or your spacecraft all have vibrations."

Materials, then, can be built to scavenge the tiny amounts of energy in their environments to dry themselves off.

You can watch the process at work in the video below. At first the water molecules are subtly impaled on the tiny spikes of the lotus leaf. As the vibration commences about halfway through the video, the water droplets at first struggle to break free — and then actually do so. In the language of materials science, the leaf's surface has gone from a Wenzel state, where it's not hydrophobic, to a Cassie state, where it is. And that's the very first time that's ever been observed in the lab.

Image: flickr/tapperboy

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Slick NASA iPhone App Puts Space in Your Pocket

Posted: 23 Oct 2009 11:37 AM PDT

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Can there ever be too many space photos? Here at Wired Science, we believe the answer is no, there can never be too many, or even enough, space photos. And now NASA is aiding our addiction by putting its huge collection of mind-blowing space photos in our pockets.

The new NASA iPhone app means that even when you are away from your computer (or telescope), you can gawk at nebulas and sunspots. NASA's image-of-the-day and astronomy-photo-of-the-day collections are right there in searchable thumbnail grids. (We like the "nebula" and "mass ejection" searches.) Plus, you can e-mail or save them to your phone. It's hard to think of a better way to get nerdy/sublime backgrounds than this app.

You can also watch videos from NASA TV of science updates, mission activity, rocket launches and other events. Another fun option is checking in on NASA's various missions with status updates and live countdowns clocks. And if you need to know exactly where the International Space Station or space shuttle is right now, NASA has you covered with their orbit tracks overlain on Google Earth or a map with political boundaries, or both.

And, of course, Twitter updates from @NASA are also right at your fingertips.

Sure, it's a space-booster public relations vehicle, but who cares? Overall, we love it. Nice job NASA!

Image: Jim Merithew / Wired.com

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Male Humpback Whales Sing Duets

Posted: 23 Oct 2009 10:44 AM PDT

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QUEBEC CITY, Canada — Like a songbird calling another out, one male humpback whale may make another change his tune.

Studying humpbacks with methods adapted from bird research has uncovered the first known instances of what look like whales responding musically to each other's songs, says Danielle Cholewiak, a researcher for the Stellwagen Bank National Marine Sanctuary based in Scituate, Massachusetts. Cholewiak and colleagues detected melodic adjustments when a solo singer encountered another singer nearby and when researchers played their song remixes for whales.

Male whales may be using music to tell another male, "Hey, I'm talking to you," Cholewiak reported Oct. 14 at the Society of Marine Mammology's biennial conference.

Cholewiak "showed short-term acoustic interactions between males — that was the new thing," said Adam S. Frankel of Marine Acoustics Inc., an independent consulting firm in Arlington, Virginia.

Among humpback whales, only males boom out long strings of repeating phrases of hums and whups and chirps. The sounds can make a boat vibrate, said Salvatore Cerchio of the Wildlife Conservation Society in New York City, who worked with Cholewiak on the new study. Scientists use the word song to describe this patterned male vocalization, just as they do for elaborate bird serenades.

Male songbirds sing at each other to claim their territory or seduce females. Though humpbacks don't defend territories, they certainly have rivalries. Typically three to eight males surround a female and battle for the position closest to her. "These guys are streaming blood," Cerchio said. "The gentle giant is a myth."

But observations so far haven't helped scientists understand whether humpbacks use songs the way birds do. Tests haven't shown male or female humpbacks consistently swimming toward or away from recorders playing songs. And scientists have yet to see humpbacks mate.

So instead, Cholewiak took a different approach, boating around a breeding ground recording and analyzing songs.

"I was drooling over what she was able to do," says Sharon Nieukirk of Oregon State University's Hatfield Marine Science Center in Newport, Oregon. Whales rarely cooperate with field biologists' experimental plans.

Cholewiak undertook the song analysis while at Cornell University, which has a renowned flock of birdsong researchers. She adapted measurements used in bird studies to analyze the humpbacks' songs. For example, the whales repeat a phrase of notes several times in one block, or "theme," before moving on to another, and Cholewiak looked at how often the whales switched among these themes.

To record whales, Cholewiak spent four winters on the small island of Socorro in the Revillagigedo Archipelago off the Pacific coast of Mexico. She dropped recorders weighted with sandbags into the ocean to eavesdrop on whales. After months, she transmitted an acoustic signal that released the recorders so they popped to the surface. Analyzing the recordings, Cholewiak could determine where the singers were and reconstruct their movements.

In the sea of sound recordings, she found 14 cases in which a male sang alone for at least 45 minutes and then continued for another 45 minutes after another male started singing. Cholewiak noticed two changes in song when humpbacks sang together.

Overall, the first singers switched more often among various musical themes when a second singer hung around. Also, the first males adjusted their songs so that the pair was more likely to sing the same theme simultaneously. When males meet, Cholewiak concluded, songs change.

When she found a male singing by himself, she attempted a playback experiment. She recorded his song and used a computer program to create a simplified version incorporating three of his themes. Then she broadcast the version to him via speakers dangling below the boat.

Confronted with simplified recordings of their songs, males tended to make their singing more even. This change meant that a male came closer to spending equal amounts of time singing each theme.

Researchers don't yet know what these changes mean, but the new work opens the way for questions about what messages whales may be communicating. If humpback songs follow the pattern of birds, the messages could get pretty macho. And females could be tuning in.

That the humpbacks appeared to respond to the playback at all was a pleasant surprise, Cholewiak says. Song playbacks had fallen into disfavor after researchers found no pattern in the movements of listeners. "I was initially very reluctant to try it," she says. Yet checking song characteristics instead of whale movements made all the difference.

Image: NOAA

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Puppets Teach Lab Safety in Music Video

Posted: 23 Oct 2009 10:00 AM PDT

After years of suffering through dull lab safety videos, a group of Berkeley students have made a film that could spare a younger generation from watching humorless people with 80's hair explain the dangers of wearing open-toed shoes while working with chemicals.

Their music video evokes the Muppets while conveying several important messages that can keep kids from getting hurt.

"Lab safety has been a real issue recently," said Patrick Bennett, who directed and edited the short film. "And a few high chemistry school teachers we knew were interested in showing stuff like the nano song in their classes."

Late last year, a UCLA lab technician was fatally wounded when a plastic syringe filled with tert-butyl lithium, which ignites upon exposure to air, broke and sprayed the flammable liquid all over her. That incident sparked a great deal of interest among chemists in updating their safety training materials.

After Bennett's group of musicians, songwriters, and puppeteers won several awards for making an educational video about nanotechnology, they turned their attention to preventing tragic accidents.

Producing their next clip took more than four months. "The music writing took quite a while, I heard the first cut back in July," Bennett said. "The video itself we filmed in mid September and didn't finish till last week."

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Space Travel: Major Milestones

Posted: 22 Oct 2009 05:00 PM PDT

<< previous image | next image >>

1957: Sputnik 1 Becomes First Artifical Satellite to Orbit Earth

The Space Age dawned a little sooner than expected with the successful launch of Sputnik 1 by the Soviet Union.

With Sputnik 1's successful deployment, the political, military and technological relationship between the Soviet Union and United States changed dramatically. The Americans immediately abandoned their Vanguard satellite project, because its intended payload was eclipsed by Sputnik's, and started anew with Explorer.

Human Spaceflight Ball in Obama’s Court

Posted: 22 Oct 2009 01:55 PM PDT

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The human spaceflight program is in your hands, Mr. President.

The blue-ribbon panel President Obama appointed to look into NASA's human spaceflight plans is done with its work, posting the final report to its website Thursday.

Weighing in at 157 pages, it examined the Bush-era Constellation program from top to bottom, although it released most of its key findings last month in an executive summary.

Top among them is that NASA does not have enough money to fund a human spaceflight program. The agency needs at least $3 billion more each year to accomplish the goals of exploring beyond low-earth orbit, while maintaining the International Space Station and other scientific programs.

While the entire human spaceflight program each citizen a mere seven cents per day, according to the report, getting more money for NASA has been a struggle. There are signs, though, that the Obama administration could provide a little more cash for human space exploration.

"[Obama] has assured me NASA will get enough money to do what it does best: Go explore the heavens," Bill Nelson, Senator from Florida said in a YouTube message to his constituents.

The panel, led by Norm Augustine, has not received a warm welcome from some members of Congress. Congress had already expressed its support for NASA's current path, so the Obama administration's attempt to rethink that plan struck many as unnecessary at best, deleterious to the space program at worst.

"While I look forward to reading the Augustine panel's final report, Congress has already made its decisions on the issues considered by the panel," said Gabrielle Giffords, a Democrat from Arizona, who heads the House subcommittee on Space, in a statement sent to Wired.com. "Now that both internal and external independent reviews have confirmed that the Constellation program is being well executed, we know what needs to be done. Let's get on with it and cease contemplating our collective navels."

Giffords, who is married to a former NASA astronaut, did indicate that she looked forward to working with Obama to "usher in a grand new era of exploration and science."

The Obama administration did not tip its hand about when or what its ultimate plans for space might be.

"The President has on numerous occasions confirmed his commitment to human space exploration, and the goal of ensuring that the nation is on a vigorous and sustainable path to achieving our boldest aspirations in space," said Nick Shapiro, a White House spokesman, in an email to Wired.com. "Against a backdrop of serious challenges with the existing program, the Augustine Committee has offered several key findings and a range of options for how the nation might improve its future human space flight activities."

Three key bones of contention remain between the Augustine panel and members of the House like Giffords. The first is the role of commercial space companies like Bigelow and SpaceX in taking astronauts to low-earth Orbit. The Augustine panel had a rather bullish view on their capabilities.

"There is little doubt that the U.S. aerospace industry, from historical builders of human spacecraft to the new entrants, has the technical capability to build and operate a crew taxi to low-Earth orbit," they wrote.

Giffords, meanwhile, said she wanted to make "clear that we are not prepared to have our astronauts' access to space held hostage to purchases of seats from non-existent commercial providers."

A second disagreement exists over the role of the Ares I rocket. Most of the Augustine members felt that it was an unwise investment. Instead, they recommended that a modified version of a heavier rocket, the Ares V Lite, should be used for trips to the moon. That would effectively kill the Ares I program, begun under Scott "Doc" Horowitz, who left the agency in 2007.

"The Committee finds the Ares V Lite used in the dual mode for lunar missions to be the preferred reference case," they wrote.

The House Science and Technology Committee chair, Bart Gordon, a Democrat from Tennessee, on the other hand, implicitly argued for the status quo, absent any findings of malfeasance. Just provide "adequate resources" and leave the program alone.

"[The Augustine] panel had assessed NASA's Constellation program and found it to be 'well managed' and a program that is 'executable and would carry out its objectives' if adequate resources are provided."

The last major difference between the Augustine commission and what Congress voted for in Constellation is the way NASA would get back to Mars. The Bush vision was to land on the moon first, learn from that experience, and head to Mars. The report gives a tepid endorsement of the viability of the plan.

"A long-duration exploration of the Moon is a step towards Mars, but not a giant step, and not the only possible step," they wrote.

The Augustine report clearly favors a different option they term the "Flexible Path," which would prioritize getting to near-earth objects first, then allow for landing-less trips to the Moon or Mars. On the criteria they created to evaluate the program, the Flexible Path clearly outscores the program of record (see image above).

Giffords, again, was ready with a response saying, "In endorsing the Constellation architecture, Congress made clear that it saw a return to the Moon as just the first step in a flexible program of human and robotic exploration of the solar system."

Even with this long-awaited report in hand, the future of NASA's human spaceflight program will remain murky until the Obama administration — or its Office for Science and Technology Policy — makes a move.

An OSTP spokesman declined to comment on the report and White House spokesman, Shapiro, could not provide a timeline for a decision.

The wheels, though, could already be turning at NASA. Spaceflight.com reported that Administrator Charles Bolden requested that a team at Marshall Spaceflight Center look into an alternative set of heavy-lift rockets known as Jupiter.

And he lauded commercial space companies in a speech to the National Association of Investment Companies earlier this week.

"What these companies, and others, are doing is nothing short of inspirational," Bolden said. "Today, we at NASA are devising ways to work with these companies and others who will come."

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Magnetic Leaves Could ID Most Polluted Routes

Posted: 22 Oct 2009 01:07 PM PDT

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PORTLAND, Oregon — Foliage on trees lining traffic routes could serve as low-tech pollution sensors, a new analysis suggests.

The exhaust of many vehicles, particularly those that burn diesel, includes copious quantities of microscopic particles of many sizes. Although particles larger than 10 micrometers in diameter are efficiently filtered by the upper respiratory system, those smaller than 2.5 micrometers across can reach areas deep within the human lung to trigger disease and inflammation, says Bernard Housen, a geophysicist at Western Washington University in Bellingham.

When Housen and university colleague Luigi Jovane analyzed leaves collected at several sites along streets in Bellingham, they found that the leaves along bus routes were as much as 10 times more magnetic than leaves collected on quieter residential streets. That boost in magnetism came from iron oxide particles in emissions that were trapped on the microscopically rough surface of the leaves, Housen reported October 18 at the annual meeting of the Geological Society of America.

magneticleaves1 Iron oxide particles smaller than 2.5 micrometers across are typically magnetic, while those larger than 10 micrometers aren't. Rain washes away no more than 30 percent of all the particles stuck on a leaf, and even ultrasonic vibrations can't fully cleanse the surface. These characteristics make tree leaves a good candidate for pollution monitoring, Housen says. Other pluses: Leaves are cheap, and they provide information about the air near ground level where people are, not high above the street where most air quality monitoring equipment is installed.

Scientists still must figure out how the number of iron oxide particles trapped by leaves relates to the total number of particles of different chemical classes in the air, says Housen. Because many air quality standards are based on exposures for short periods of time, such as eight-hour or 24-hour intervals, researchers must also figure out how to estimate short-term air quality from leaves, which accumulate particles throughout their growth.

Images: 1) One of the Fe-oxide spheres produced by combustion, collected with a double-sided tape collector. / Rachel Housen, Whatcom Middle School/Bellingham High School. 2) Particles on the surface of a leaf. / Sadie Belica, Western Washington University.

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Farthest Galaxy Cluster Ever Detected

Posted: 22 Oct 2009 12:08 PM PDT

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Captured by NASA's Chandra X-ray Observatory and combined with data from infrared and optical telescopes, this image shows the farthest galaxy cluster ever detected. Designated JKCS041, the cluster is located 10.2 billion light-years from Earth, beating the previous distance record by a billion light-years.

Astronomers think JKCS041 formed just about as early as was feasible.

"This object is close to the distance limit expected for a galaxy cluster," said Stefano Andreon of the National Institute for Astrophysics in Milan, Italy, in a press release. "We don't think gravity can work fast enough to make galaxy clusters much earlier."

This cluster was first spotted by the United Kingdom Infrared Telescope in 2006, and then by optical telescopes such as the Very Large Telescope in Chile. But until Chandra took a look, it wasn't clear if it was a full-blown legitimate galaxy cluster rather than one still in the process of forming or a line of galaxies viewed head on. The image above is a composite of all three types of data.

Because JKCS041 is so old, it will help scientists understand what was happening at this critical time in the formation of the universe, when it was only about a fourth as old as it is today. But if more super-old clusters can be found, scientists can begin testing cosmological theories.

"This discovery is exciting because it is like finding a Tyrannosaurus rex fossil that is much older than any other known," said Ben Maughan of the University of Bristol in Britain, co-author of a paper describing the cluster in Astronomy & Astrophysics. "One fossil might just fit in with our understanding of dinosaurs, but if you found many more, you would have to start rethinking how dinosaurs evolved. The same is true for galaxy clusters and our understanding of cosmology."

Image: X-ray: NASA/CXC/INAF/S.Andreon et al. Optical: DSS; ESO/VLT

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Killer Disease Short-Circuits Frog Hearts

Posted: 22 Oct 2009 11:00 AM PDT

A terrible disease that could drive many frogs to extinction appears to kill by interrupting the flow of nutrients through their normally porous skins, which ultimately causes their hearts to shut down, say scientists.

Until now, it wasn't known how the disease, called chytridiomycosis, does its damage.

"Understanding the pathogenesis is fundamental to understanding this disease," said Jamie Voyles, a James Cook University biologist and co-author of the paper published Thursday in Science. "Now we can start to develop treatments for frogs in captivity. If it works out, we could potentially treat frogs where outbreaks are happening. We could perhaps help frogs get through the initial catastrophic declines."

First identified in 1993, chytridriomycosis — chytrid for short — is caused by Batrachochytrium dendrobatidis, a highly virulent fungus that remains in the environment, even after killing its amphibian hosts. It does this with frightening efficiency: In less than two decades, it has killed about 95 percent of percent of all frogs in Colombia and Panama, and driven some 30 species in the Atelopus genus alone to extinction.

Frogs are especially vulnerable, but chytrid affects most amphibian species, and after being spread by the global trade in African clawed toads, is now found in every continent except Antarctica.

Though it's not the only threat faced by amphibians, who are also squeezed by climate change, habitat destruction and humanity's harnessing of approximately one-half of Earth's fresh water, chytrid is perhaps the worst. Unless something can be done about it, many amphibians, whose evolutionary lineage can be directly traced to a time before birds or mammals or even dinosaurs, will almost certainly vanish.

Until now, it wasn't clear how chytrid kills.

"It's a fantastic paper," said Paul Daszak, a disease ecologist with the Wildlife Trust who was not involved in the research. "It finally clinches the cause of death. This isn't any old disease; it's emerging on multiple continents, and is probably the most significant disease we've ever seen in wildlife. It's a breakthrough."

Chytrid has remained a mystery in part because amphibian researchers receive relatively little funding, but also because its victims' bodies shut down so completely that it's difficult to know the precise cause of death.

In earlier research on diseased frogs, Voyles' team had noticed imbalances of electrolytes, the compounds that conduct electrical charges through cells. In frogs as in humans, a healthy electrolyte balance is needed to keep the heart pumping.

Because amphibians absorb electrolytes through their skin, the researchers suspected that the fungus, which resides on their skin, was to blame.

To study the connection, they first measured electrolyte flow across the skin of infected green tree frogs, and found that it dropped by half as the disease progressed. This produced a drop of 20 percent in blood levels of sodium and 50 percent in potassium, two key electrolytes.

Then the researchers implanted miniaturized cardiac activity recorders inside the chests of another group of frogs. The monitors produced frog versions of electrocardiograms, readouts familiar to people who've had their hearts monitored. When the frogs were infected, their cardiac systems malfunctioned in tandem with their falling electrolytes.

"Changes in sodium and potassium basically led to a failure of the electrical system. This is exactly what we see in humans as well. It's a failure of the electrical system, leading to mechanical failure. If you don't have a normal electrical system pacing the heart, it won't pump blood," said Wyatt Voyles, a University of New Mexico cardiologist and co-author of the study.

Exactly how the fungus interferes with electrolyte transport is unknown. The researchers suspect it's the result of direct cell damage, or the release of a fungal toxin.

"Helping us understand the cause of death is really a step forward," said Louise Rollins-Smith, a Vanderbilt University microbiologist who studies amphibian immune systems. She was not involved in the study.

Electrolyte supplements slightly prolonged the life of diseased frogs in the study, and Rollins-Smith said the findings may help scientists develop treatments for chytrid. Though probably not practical at the ecosystem level, such treatments could be used on captive frogs bred to restore dwindling wild populations.

The research could also help researchers understand why some species or sub-species are especially resistant to chytrid, and help to guide conservation efforts.

But Jamie Voyles cautioned that stopping chytrid isn't enough to save amphibians. "This disease is important, but it's important to recognize that there are many threats. Unfortunately, there's no silver bullet."

Images: 1. Flickr/Brandon Keim 2. Above, a healthy frog and its skin; below, an infected frog and its skin, from Science.

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Citation: "Pathogenesis of Chytridiomycosis, a Cause of Catastrophic Amphibian Declines." Jamie Voyles, Sam Young, Lee Berger, Craig Campbell, Wyatt F. Voyles, Anuwat Dinudom, David Cook, Rebecca Webb, Ross A. Alford, Lee F. Skerratt, Rick Speare. Science, Vol. 326 No. 5952, October 23, 2009.

Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecosystem and planetary tipping points.